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United States Patent |
5,778,124
|
Nedstedt
|
July 7, 1998
|
Device for optical connection of an optical element, for example an
optical fibre, with a lens
Abstract
A device for optical connection of an optical element, for example an end
portion of an optical fiber (2), with a spherical lens (4) comprises a
connector element (14). The connector element has a surface for defining
the position of the spherical lens and a surface for defining the position
of the optical element in relation thereto. A surface of the connector
element for defining the position of the spherical lens (4) are
constituted by a circular edge surface (18) formed with a radius.
Inventors:
|
Nedstedt; Bo (Parkgatan, SE)
|
Assignee:
|
Formex AB (Anderstorp, SE)
|
Appl. No.:
|
963881 |
Filed:
|
November 4, 1997 |
Foreign Application Priority Data
Current U.S. Class: |
385/79; 359/819; 385/35; 385/61; 385/93 |
Intern'l Class: |
G02B 006/32 |
Field of Search: |
385/35,61,79,93
359/819
|
References Cited
U.S. Patent Documents
3904277 | Sep., 1975 | Phillips et al. | 359/819.
|
4781431 | Nov., 1988 | Wesson et al. | 385/79.
|
4889399 | Dec., 1989 | Mariani et al. | 385/35.
|
4988375 | Jan., 1991 | Bornhauser | 385/35.
|
5107537 | Apr., 1992 | Schriks et al. | 385/93.
|
5247595 | Sep., 1993 | Foldi | 385/35.
|
5459805 | Oct., 1995 | Foster | 385/35.
|
Foreign Patent Documents |
9101877 | Aug., 1991 | SE.
| |
2054896 | Feb., 1981 | GB | 385/35.
|
2221324 | Jan., 1990 | GB | 385/35.
|
Primary Examiner: Lee; John D.
Attorney, Agent or Firm: Baker & Daniels
Parent Case Text
This is a continuation of application Ser. No. 08/614,531, filed Mar. 13,
1996 (abandoned).
Claims
What is claimed is:
1. A device for optical connection of an optical element with a spherical
lens, the device comprising:
a connector element having a first surface for defining the position of the
spherical lens and a second surface for defining the position of the
optical element in relation to the spherical lens thereby relatively
positioning the optical element and the spherical lens, wherein the first
surface of the connector element for defining the position of the
spherical lens comprises a circular edge surface, the circular edge
surface defining a circular opening and having a cross sectional profile
which defines an arc whereby the circular edge surface forms a convex
rounded edge.
2. A device as claimed in claim 1 wherein the arc defined by the cross
sectional profile of the circular edge surface is formed with a radius of
about 0.25 mm.
3. A device as claimed in claim 2 further comprising a fixing element for
fixing the spherical lens in a position in which the spherical lens
contacts the circular edge surface of the connector element.
4. A device as claimed in claim 2 wherein the device further comprises a
retainer for fixing the optical element in a predetermined position in
relation to a reference surface of the retainer and that the second
surface of the connector element for defining the position of the optical
element in relation to the spherical lens engages the reference surface of
the retainer.
5. A device as claimed in claim 1 further comprising a fixing element for
fixing the spherical lens in a position in which the spherical lens
contacts the circular edge surface of the connector element.
6. A device as claimed in claim 5 wherein the fixing element comprises a
locking element comprising a rigid material the locking element engaging
the connector element and an elastic material element positioned between
the locking element and the spherical lens.
7. A device as claimed in claim 6, wherein the device further comprises a
retainer for fixing the optical, element in a predetermined position in
relation to a reference surface of the retainer and that the surface of
the connector element for defining the position of the optical element in
relation to the spherical lens engages the reference surface of the
retainer.
8. A device as claimed in claim 5, wherein the device further comprises a
retainer for fixing the optical element in a predetermined position in
relation to a reference surface of the retainer and that the second
surface of the connector element for defining the position of the optical
element in relation to the spherical lens engages the reference surface of
the retainer.
9. A device as claimed in claim 1 wherein the device further comprises a
retainer for fixing the optical element in a predetermined position in
relation to a reference surface of the retainer and that the second
surface of the connector element for defining the position of the optical
element in relation to the spherical lens engages the reference surface of
the retainer.
10. A device as claimed in claim 9 wherein the optical element comprises an
optical fibre, and the retainer further comprises a sleeve having a flat
end surface connected with the reference surface of the retainer and
coinciding with an end surface of the optical fibre.
11. A device as claimed in claim 10, wherein the connector element further
comprises support surfaces which are positioned at a distance from the
second surface engaging the reference surface of the retainer and are
adapted to engage the retainer for maintaining the correct position
thereof.
12. A device as claimed in claim 9 wherein the reference surface of the
retainer and the second surface of the connector element engaging the
reference surface of the retainer comprise cooperating cylindrical
surfaces and contact surfaces extending transversely of respective axes of
the cylindrical surfaces.
13. A device as claimed in claim 12 wherein the surfaces extending
transversely of the axes of the cylindrical surfaces comprise an end
surface of the connector element and an opposite surface on a flange
projecting from the cylindrical surface of the retainer.
14. A device as claimed in claim 12, wherein the surfaces extending
transversely of the axes of the cylindrical surfaces comprise an end
surface of the retainer coinciding with an end surface of the optical
fibre and an opposite surface on the connector element.
15. A device for optical connection of an optical element with a spherical
lens, the device comprising:
a connector element having a first surface for defining the position of the
spherical lens and a second surface for defining the position of the
optical element in relation to the spherical lens thereby relatively
positioning the optical element and the spherical lens, wherein the first
surface of the connector element for defining the position of the
spherical lens comprises a circular edge surface, the circular edge
surface defining a circular opening and having a cross sectional profile
which defines an arc whereby the circular edge surface forms a rounded
edge: and
a retainer for fixing the optical element in a predetermined position in
relation to a reference surface of the retainer and wherein the second
surface of the connector element engages the reference surface of the
retainer and comprises a conical surface tapering in the direction of the
spherical lens.
16. A device for optical connection of an optical element with a spherical
lens, the device comprising:
a connector element having a first surface for defining the position of the
spherical lens and a second surface for defining the position of the
optical element in relation to the spherical lens thereby relatively
positioning the optical element and the spherical lens, wherein the first
surface of the connector element for defining the position of the
spherical lens comprises a circular edge surface, the circular edge
surface defining a circular opening and having a cross sectional profile
which defines an arc whereby the circular edge surface forms a rounded
edge: and
a retainer for fixing the optical element in a predetermined position in
relation to a reference surface of the retainer and wherein the second
surface of the connector element engages the reference surface of the
retainer; the reference surface and the second surface comprising
cooperating cylindrical surfaces and contact surfaces extending
transversely of respective axes of the cylindrical surfaces, wherein the
surfaces extending transversely of the axes of the cylindrical surfaces
comprise contact surfaces for a direct engagement between the spherical
lens and end surfaces of the retainer and the optical element.
17. A device for optical connection of an optical element with a spherical
lens, the device comprising:
a connector element having a first surface for defining the position of the
spherical lens and a second surface for defining the position of the
optical element in relation to the spherical lens thereby relatively
positioning the optical element and the spherical lens, wherein the first
surface of the connector element for defining the position of the
spherical lens comprises a circular edge surface, the circular edge
surface defining a circular opening and having a cross sectional profile
which defines an arc whereby the circular edge surface forms a rounded
edge; and wherein the connector element is adapted to cooperate with
guiding means, the guiding means being adapted to cooperate with another
connector element comprising an optical element connected with a lens for
optical connection of the optical elements of the connector elements to
each other through the lenses of the connector elements.
18. A device as claimed in claim 17 wherein each connector element has a
contact surface extending perpendicular to the axis of the connector
elements the contact surfaces being adapted for mutual engagement.
19. A device as claimed in claim 17, wherein the guiding means comprises a
sleeve enclosing adjacent portions of the connector elements.
20. A device as claimed in claim 17, wherein the guiding means comprises
guiding pins.
Description
The present invention relates to a device for optical connection of an
optical element, for example an end portion of an optical fibre, with a
spherical lens.
In fibre optical systems there are different points at which optical
connections between the different optical elements included in the system.
Thus, there are required optical connections between different lengths of
optical fibres, between an optical fibre and a light source, for example a
diode, between an optical fibre and a light detector etc. Each connection
must be established while using very great accuracy if the losses shall be
kept at a minimum. Of course, the problem of providing a correct
connection is emphazised by the fact that optical fibres have a very small
cross sectional area and that also small deviations from a correct
position between two fibre end portions which shall be connected with each
other cause substantial losses. It is important especially to avoid
angular deviations between the fibres, i.e. it is important that the
fibres which are connected with each other are positioned on the same
optical axis.
Different devices for providing a correct connection of optical fibres with
each other and with other optical elements have been suggested. Such
previously known devices comprise lens systems in which the light beam is
magnified so that the light transmission in the connection takes place at
a sectional area which is magnified several times providing for a
corresponding reduction of the sensitivity to deviations from the correct
position. Thereby, it is a drawback that the connection of two fibre end
portions to each other requires instead of one single connection, i.e. the
connection between the fibre end portions, an optical connection of the
fibre end portions to one lens each and an optical connection of the
lenses to each other, i.e. three connections. Thereby, it is important
that the optical fibres and the lenses are positioned on the same optical
axis as well as that the end surfaces of the fibres are positioned in the
focus of the lens in question. Thus, the connections between the optical
fibres and the lenses constitute the most sensitive parts of the
connection system while the optical connection of the lenses to each other
can easily be provided without errors.
Different devices for connecting an optical element with a lens are
previously known. A drawback of previously known connection devices is the
fact the they are either complicated in respect of their construction or
offer insufficient accuracy with regard to the requirement that the
optical element and the lens shall be positioned on the same optical axis
and that the optical element shall be positioned in the focus of the lens.
A previously known device for optical connection of an optical element,
for example an end portion of an optical fibre, with a spherical lens
comprises a connector element having one surface for determining the
position of the spherical lens and one surface for determining the
position of the optical element in relation to the spherical lens and
thereby for determining the relative position between the optical element
and the spherical lens. In prior art devices of this kind it is a drawback
that the surface for determining the position of the spherical lens is
either of such a design that the position of the lens is not determined
with sufficient accuracy or is of such a design that the surface of the
lens is subjected to too large stresses.
The object of the invention is to provide a device for optical connection
of an optical element, for example an end portion of an optical fibre,
with a spherical lens in which the surface of the connector element for
defining the position of the spherical lens is of such a design that the
above drawbacks of the prior art devices are obviated.
In order to comply with this object the device according to the invention
is characterized in that the surface of the connector element for defining
the position of the spherical lens is constituted by a circular edge
surface formed with a radius, i.e., the edge defining the circular opening
has a cross sectional profile which defines an arc whereby the circular
edge surface forms a rounded edge.
A surface of this kind provides that the spherical lens is connected with
the optical element, for example the end portion of an optical fibre, in
such a way that the optical element and the lens are positioned on the
same optical axis and that the lens takes a correct position in relation
to the optical element with regard to the relationshiop between the
optical element and the focus of the lens.
It is suitable that the radius of the circular edge surface is about 0.25
mm.
In a preferred embodiment of the device according to the invention the
device comprises a fixing element for fixing the spherical lens in a
position in which the spherical lens contacts the circular edge surface of
the connector element, formed with a radius, the fixing element suitably
comprising a locking element engaging the connector element, the locking
element consisting of a rigid material, and an elastic material element
positioned between the locking element and the spherical lens.
It is suitable that the device according to the invention comprises a
retainer for fixing the optical element in a predetermined position in
relation to reference surfaces of the retainer and that the surfaces of
the connector element for defining the position of the optical element in
relation to the spherical lens engage the reference surfaces of the
retainer. Thereby, the surface of the connector element engaging the
reference surface of the retainer can be constituted by a conical surface
tapering in the direction of the spherical lens. The reference surface of
the retainer and the surface of the connector element engaging the
reference surface of the retainer can as an alternative be constituted by
cooperating cylindrical surfaces and by engagement surfaces extending
transversely in relation to the axes of the cylindrical surfaces.
The device according to the invention can be used in connection with
different combinations of optical elements and a spherical lens, for
example for transmitting a light beam from a diode to an optical fibre
through two spherical lenses. Thereby there are used two devices according
to the invention, one device for connecting the diode to the spherical
lens and one device for connecting the optical fibre with another
spherical lens. The correct relative position between the two connector
elements for transmitting the light beam between the spherical lenses is
in a known manner provided by means of guiding pins or other guiding
surfaces arranged on the connector elements. It is realized that the
relative position between the spherical lenses does not require any
adjustment of such a great accuracy as the relative position between the
lens and the optical element connected therewith.
The invention is described in the following with reference to the
accompanying drawings.
FIGS. 1, 2, 3, and 4 are schematic sections of different embodiments of
devices according to the invention for optical connection of an optical
element with a spherical lens.
FIGS. 5, 6, and 7 are schematic sections of two devices according to the
invention, connected with each other for connecting two optical elements
with each other through two spherical lenses.
FIGS. 8 and 9 are sections of two different embodiments of devices for
fixing a spherical lens in connector devices according to the invention.
FIG. 10 is an enlarged sectional view of a spherical lens seated against a
circular edge surface formed with a radius.
The device according to the invention is adapted to be included in a system
for connecting a first optical element, for example an optical fibre, with
another optical element, for example another optical fibre, in which
system the optical elements are connected with one lens each, so that the
transmission of the light between the optical elements takes place through
the lenses. The embodiment of a device according to the invention
schematically shown in section in FIG. 1 is used for connecting an optical
fibre 2 with a spherical lens 4. The end portion of the optical fibre 2 is
enclosed in a fibre retainer 6 designed as a sleeve. The fibre retainer 6
is cylindrical along the main portion of its outer surface and has at its
right end in the figure a conical reference surface 8 connecting with a
flat end surface 10 of the fibre retainer 6. In the embodiment shown in
FIG. 1 the main part of the fibre retainer 6 consists of metal while the
flat end surface 10 is formed by an insert 12 of ceramic material moulded
into the fibre retainer.
The optical fibre 2 is fixed in the fibre retainer in a known manner, for
example by means of an adhesive, the end surface of the optical fibre 2
being positioned in the same plane as the flat end surface 10 of the
insert 12. A correct position of the end surface of the optical fibre 2
can be provided by fixing the fibre with the end portion projecting
somewhat outside the plan end surface 10, whereupon the fibre is ground to
the plane of the end surface 10. The flat end surface 10 of the fibre
retainer has an exactly predetermined position in relation to the conical
reference surface 8 of the fibre retainer, and when the end surface of the
fibre 2 is positioned in the plane of the end surface 10, the end surface
of the fibre 2 will consequently be related to the conical reference
surface 8 in a predetermined way.
The device for optical connection of the optical fibre 2 with the spherical
lens 4 comprises in addition to the fibre retainer 6 a connector element
14. The connector element 14 is provided with surfaces for determining the
relative position between the fibre retainer 6 and thereby the optical
fibre 2 and the spherical lens 4. The surface of the connector element 14
for defining the position of the fibre retainer 6 and thereby the optical
fibre 2 is constituted by a conical surface 16 tapering in the direction
of the spherical lens 4. Thus, the conical surface 16 is adapted to engage
the conical reference surface 8 of the fibre retainer 6 in order to
exactly define the position of the fibre retainer 6 in the connector
element 14. The surface for defining the position of the spherical lens in
the connector element 14 and thereby for defining the relative position
between the optical fibre 2 and the spherical lens 4 is constituted by a
circular edge surface 18 formed with a radius. The circular edge surface
is formed with a radius of about 0.25 mm and provides an extremely
accurate definition of the position of the spherical lens without damaging
the surface of the spherical lens by subjecting the surface to too large
stresses.
The fibre retainer 6 and the spherical lens 4 are maintained in firm
engagement with the conical surface 16 and the edge surface 18 formed with
a radius, respectively, by means of arrangements not shown in detail in
FIG. 1. In respect of the fibre retainer 6 these arrangements can be
constituted by a conventional sleeve nut engaging a shoulder on the fibre
retainer 6, not shown in the drawing, while said arrangement in respect of
the spherical lens can be constituted by devices of the kind shown in
FIGS. 7 and 8.
The conical surface 16 and the edge surface 18 formed with a radius are
positioned in relation to each other so that the optical fibre 2 and the
spherical lens 4 are positioned on the same optical axis and at such an
axial distance from each other that the end surface of the optical fibre 2
is in the focus of the spherical lens 4, when the conical reference
surface 8 and the spherical lens 4 engage the surface belonging thereto.
In order to make sure that the fibre retainer 6 is oriented so that the
portion of the optical fibre received in the fibre retainer is over its
total length positioned on the optical axis common with the optical axis
of the spherical lens, the optical element 14 can be provided with support
surfaces 22 adapted to engage the fibre retainer 6 at the end of the fibre
retainer 6 opposite from the conical reference surface 8.
In a plane outside the spherical lens 4 the connector element 14 has a
contact surface 24. The contact surface 24 is adapted to engage a
corresponding surface of another connector element to be connected with
the connector element 14 for providing an optical connection of the
optical fibre 2 with another optical element, for example another optical
fibre, a diode or a light sensor device, included in the other connector
element. It is thereby important that the contact surface 24 is exactly
perpendicular to the axis of the conical surface 16 and the edge surface
18, and this can be provided by manufacturing the surfaces 16 and 18 and
the contact surface 24 in one and the same machine and in a continuous
operation.
The embodiment of the device according to the invention shown in FIG. 2 is
like the device according to FIG. 1 used for connecting an optical fibre
2a with a spherical lens 4a. The end portion of the optical fibre 2a is
enclosed in a fibre retainer 6a in the form of a sleeve. The fibre
retainer 6a has a cylindrical outer surface 8a connecting with a flat end
surface 10a on the fibre retainer 6a. As is the case in the embodiment
according to FIG. 1, the main portion of the fibre retainer 6a is
constituted by metal while a part of the flat end surface 10a consists of
an insert 12a of ceramic material moulded into the fibre retainer.
The optical fibre 2a can be fixed in the fibre retainer 6a according to the
same principles as the optical fibre 2 is fixed in the fibre retainer 6
according to FIG. 1, and the correct position of the end surface of the
optical fibre 2a can be provided in the same way as described with
reference to FIG. 1.
At its outer surface the retainer 6a has an annular flange 26, having an
annular side 28 which forms in relation to the cylindrical reference
surface 8a a perpendicular reference surface 28 which takes an exactly
predetermined position in relation to the flat end surface 10a of the
fibre retainer and thereby in relation to the end surface of the fibre 2a.
Thus, the end surface of the fibre 2a takes a predetermined position in
relation to the cylindrical reference surface 8a as well as to the annular
reference surface 28 extending transversely thereto.
As is the case in the embodiment according to FIG. 1 the device for optical
connection of the optical fibre 2a with the spherical lens 4a in the
device according to FIG. 2 includes in addition to the fibre retainer 6a a
connector element 14a. Also in this embodiment the connector element 14a
is provided with surfaces for defining the relative position between the
fibre retainer 6a and the optical fibre 2a connected therewith and the
spherical lens 4a. The surfaces of the connector element 4a for defining
the relative position between the fibre retainer 6a and thereby the
optical fibre 2a and the spherical lens 4a are constituted by a
cylindrical surface 30 defining an opening for receiving the retainer 6a
and an end surface 32 extending perpendicular to the cylindrical surface
30 and surrounding the opening for receiving the retainer 6a and a
circular edge surface 18a formed with a radius, said edge surface defining
the position of the spherical lens 4a in the connector element 14a. The
cylindrical surface 30 and the circular edge surface 18a formed with a
radius are positioned on the same axis.
The spherical lens 4a and the fibre retainer 6a are maintained in
engagement with the edge surface 18a and the surfaces 30 and 32,
respectively, by elements which are not shown in detail in FIG. 2. Like in
the embodiment according to FIG. 1 these elements can be constituted by a
conventional sleeve nut and devices of the kind shown in FIGS. 7 and 8. As
in the embodiment according to FIG. 1 the optical fibre 2a and the
spherical lens 4a are positioned on the same optical axis and at such a
distance from each other that the end surface of the optical fibre 2a is
positioned in the focus of the spherical lens 4a.
In a plane outside the spherical lens 4a the connector element 14a has a
contact surface 24a having the same design and function as the contact
surface 24 in the embodiment according to FIG. 1.
Also the embodiment of the device according to the invention shown in FIG.
3 is intended for connecting an optical fibre 2b with a spherical lens 4b.
The end portion of the optical fibre 2b is also in this embodiment
enclosed in a fibre retainer 6b in the form of a sleeve. The fibre
retainer 6b has a cylindrical outer surface 8b which connects with a flat
end surface 10b on the fibre retainer 6b. Unlike the embodiment according
to FIGS. 1 and 2 the main part of the fibre retainer 6b is in the
embodiment according to FIG. 3 constituted by a cylindrical element 12b of
ceramic material. The outer end portion of the cylindrical element 12b
consisting of ceramic material is forced and fixed into an element 13
consisting of metal.
The optical fibre 2a is fixed in the fibre retainer 6b and the correct
position of the end surface of the optical fibre 2b can be provided
according to the same principles as described with reference to FIGS. 1
and 2. Thus, the end surface 10b of the fibre retainer 6b will take an
exactly predetermined position in relation to the end surface of the fibre
2b. Thereby, the end surface of the fibre 2b is in a predetermined way
related to the cylindrical reference surface 8b as well as to the flat end
surface 10b of the retainer.
Also the device for optical connection of the optical fibre 2b with the
spherical lens 4b shown in FIG. 3 comprises in addition to the fibre
retainer 6b a connector element 14b. The connector element 14b is provided
with surfaces for defining the relative position between the fibre
retainer 6b and therewith the optical fibre 2b and the spherical lens 4b.
The surfaces of the connector element 14b for defining the relative
position between the fibre retainer 6b and thereby the optical fibre 2b
and the spherical lens 4b are constituted by a cylindrical surface 30b
forming an opening for receiving the retainer 6b and a bottom surface 32b
perpendicular to the cylindrical surface 30b and forming a bottom in the
opening formed by the cylindrical surface 30b for receiving the retainer
6b and a circular edge surface 18b formed with a radius. Thus, the
retainer 6b and thereby the optical fibre 2b are defined with regard to
their positions in the connector element by the fact the cylindrical
surface 8b of the retainer 6b engages the cylindrical surface 30b of the
connector element 14b and by the fact that the end surface 10b of the
retainer 6b engages the bottom surface 32b of the connector element 14b,
and the position of the spherical lens 4b is defined in the connector
element 14b by the engagement with the edge surface 18b.
As in the embodiment according to FIGS. 1 and 2 the fibre retainer 6b can
be maintained in engagement with the surfaces 30b and 32b by means of a
conventional sleeve nut, and the spherical lens 4b can be maintained in
engagement with the edge surface 18b by means of devices of the kind shown
in FIGS. 8 and 9.
In a plane outside the spherical lens 4b the connector element 14b has a
contact surface 24b of the same design and function as the contact
surfaces 24 and 24a in the embodiments according to FIG. 1 and 2,
respectively.
The embodiment of the device according to the invention shown in FIG. 4 is
intended for connecting a diode 34 with a spherical lens 4c. Like the
devices according to FIGS. 1 and 2 the device comprises a connector
element 14c having a circular edge surface 18c formed with a radius, a
cylindrical reference surface 30c and an annular reference surface 32c
extending perpendicular thereto. In addition to the connector element 14c
the device according to the embodiment of FIG. 4 comprises a retainer for
the diode 34 in the form of a sleeve 36. The sleeve 36 has a cylindrical,
outer reference surface 8c adapted to engage the cylindrical surface 30c
of the connector element in order to define the position of the diode so
that the optical axis thereof coincides with the axis of the cylindrical
surface 30c. As the axis of the cylindrical surface 30c coincides with the
axis of the circular edge surface 18c formed with a radius, the focus of
the lens 4c will be positioned on the optical axis of the diode. In order
to define the axial distance of the diode 34 from the spherical lens 4c
the sleeve 36 is provided with an outer, annular flange 38 engaging the
reference surface 32c of the connector element by means of a side surface
40. In the embodiment shown in FIG. 4 there is used a sleeve nut 42 for
fixing the sleeve 36 and thereby the diode 34 in the position in which the
surface 40 of the flange 38 engages the surface 32c. Also in this
embodiment the reference surfaces provide for a correct relative position
between the diode 34 and the spherical lens 4c, so that the diode and the
lens are positioned on the same optical axis and at a correct axial
distance from each other. The sleeve 36 can be fixedly connected with the
diode 34 and can be adapted to obtain its final shape after having been
connected with the diode, for example by the fact the cylindrical
reference surface 8b and the annular reference surface 40 of the flange
are by turning provided with their final shape after the sleeve has been
connected with the diode.
FIG. 5 schematically illustrates the connection of two optical fibres 2a
with each other by means of devices according to the invention. Thus, the
devices are constituted by two devices of the kind shown in FIG. 2 which
are connected with each other with the contact surfaces 24a in engagement
with each other and the devices centered in relation to each other by
means of guiding pins 44. The light beam from one of the optical fibres is
magnified by the spherical lens optically connected with the fibre and
departs from the lens as a parallel beam having a section which is several
times larger than the beam received from the optical fibre, the beam from
the lens being received by the other spherical lens which reduces the beam
to the optical fibre connected with the second lens. Because of the
magnification of the beam in the transition area between the optical
fibres the losses in the transition area are reduced.
In FIG. 6 there is shown the connection of two devices of the kind shown in
FIG. 2, wherein the devices are centered in relation to each other by
means of an outer socket 46 instead of by means of guiding pins. The
socket 46 makes it possible to provide a correct position of the devices
without an engagement between the end surfaces 24a of the devices which
thereby must not be designed with special precision. The axial distance
between the devices can be determined in any conventional way not shown in
the figure.
In FIG. 7 there is shown the connection between a device of the kind shown
in FIG. 2 and a device of the kind shown in FIG. 4.
In FIGS. 8 and 9 there are illustrated suitable devices for retaining the
spherical lens 4 in engagement with the circular edge surface 18 formed
with a radius.
In the embodiment according to FIG. 8 the spherical lens 4 is retained in
engagement with the circular edge surface 18 formed with a radius by means
of a plug 48 having an outer thread and being threaded into a hole 50. The
plug 48 has at its end which is adapted to engage the spherical lens 4 a
ring 52 consisting of elastic material and resiliently forcing the
spherical lens 4 against the edge surface 18.
In the embodiment according to FIG. 9 the spherical lens 4 is retained in
engagement with the edge surface 18 by means of a spring ring 54 which is
mounted in a groove 56 in a hole 58 connecting with the circular edge
surface 18 formed with a radius. Between the spring ring 54 and the
spherical lens 4 there is provided a ring 60 of elastic material
resiliently forcing the spherical lens 4 against the edge surface 18.
The embodiment according to FIG. 9 illustrates that the relative position
between the spherical lens 4 and the retainer 6 with the optical fibre 2
fixed therein can be determined also by a direct engagement between the
spherical lens 4 and the end surfaces of the retainer and the fibre. In
this case the spherical lens has such a refractive index that the focus is
positioned in the surface of the lens.
The invention can be modified within the scope of the following claims and
can be adapted to different combinations of connections between optical
fibres and other optical elements.
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